Evidence suggests that known transfer closure valves do not prevent material, for example, powder from being undesirably discharged into the environment.
In a known type of transfer valve, a so-called "double door principle" is employed, in which a barrel to be filled or emptied is closed by a lid which is rotatable through a given angle. The barrel with the lid secured thereto is mounted on the transfer valve and is then placed in position and rotated, causing the lid of the barrel to be released. A lid of the valve and the lid of the barrel, are then pivoted out together, the transfer valve is then opened and a filler pipe is then passed through the transfer system causing the material in the barrel to be transferred through the opened transfer system into another barrel.
A disadvantage of the known system referred to above is that the barrel must be rotated for docking with the transfer valve, with the danger of wear and tear on the sealing means, so that with repeated use, the tightness of the sealing can no longer be guaranteed.
Also, the expense of providing the mechanical means needed for docking and rotation of the barrel to be filled or emptied, is relatively high. Especially where the barrel is large and heavy it is undesirable for the barrel first to be raised and then to be rotated through an angle of, for example, 60.degree. C. in order to achieve the docking and opening of the transfer valve. Further, the friction generated by the surfaces rubbing against each other can cause particles to be released undesirably into the environment. At the same time the problem arises of particles which are released as a result of said surfaces rubbing against each other, getting into the product, with which a barrel is to be filled, so that it is undesirably soiled.
It is therefore an object of the present invention to provide a transfer closure valve of the type mentioned in the first paragraph of this specification, with which hazardous materials can be more safely transferred and with substantially less expensive mechanical means.